unit1.pas

已知多个点坐标

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Math, Buttons, ExtCtrls;

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    Memo2: TMemo;
    Panel1: TPanel;
    Button2: TButton;
    LabeledEdit1: TLabeledEdit;
    LabeledEdit2: TLabeledEdit;
    BitBtn1: TBitBtn;
    BitBtn2: TBitBtn;
    Splitter1: TSplitter;
    procedure Button2Click(Sender: TObject);
    procedure BitBtn1Click(Sender: TObject);
    procedure BitBtn2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
  fTPoint = record
            x:Extended;
            y:Extended;
      end;
  yTPoint = record
            x,y,r:Extended;
      end;

var
  Form1: TForm1;
  Num:integer;
  pt:array[1..1024]of fTPoint;
  yuanNum:integer;
  yuan:array[1..1024] of yTPoint;

implementation

{$R *.dfm}



procedure Getit(x1,y1,x2,y2,x3,y3:Extended;var x,y,r:Extended);
begin
  // center x
  x := ((y3-y1)*(y2-y1)*(y2-y3)+(x1*x1-x2*x2)*(y2-y3)+(x2*x2-x3*x3)*(y2-y1))
       /(2*((x1-x2)*(y2-y3)+(x2-x3)*(y2-y1)));

  // center y
  if y2-y1 <> 0 then
    y := ((x1-x2)/(y2-y1)*(2*x-(x1+x2))+y1+y2)/2
  else
    y := ((x2-x3)/(y3-y2)*(2*x-(x2+x3))+y2+y3)/2;

  r:=Power((x1-x)*(x1-x)+(y1-y)*(y1-y), 0.5)

end;




procedure TForm1.Button2Click(Sender: TObject);
var
  i,j,k,l:integer;
  str0,str1,str2:string;
  x,y,r:extended;
  canuse:boolean;


begin
  yuanNum:=0;
  for i:=1 to Num do
   for j:=i+1 to Num do
    for k:=j+1 to Num do
      begin

        if (i<>j) and (i<>k) and (j<>k) then
         if ((pt[i].y-pt[j].y)*(pt[j].x-pt[k].x)<>(pt[j].y-pt[k].y)*(pt[i].x-pt[j].x)) then
          begin
          Getit(pt[i].x,pt[i].y,pt[j].x,pt[j].y,pt[k].x,pt[k].y,x,y,r);

          if yuanNum=0 then
           begin
             inc(yuanNum);
             yuan[yuanNum].x:=x;
             yuan[yuanNum].y:=y;
             yuan[yuanNum].r:=r;
           end
          else
           canuse:=true;
           for l:=1 to yuanNum do
             if (yuan[l].x =x) and (yuan[l].y =y) and (yuan[l].r =r) then canuse:=false;
           if canuse then
             begin
             inc(yuanNum);
             yuan[yuanNum].x:=x;
             yuan[yuanNum].y:=y;
             yuan[yuanNum].r:=r;
             end;
          end;
      end;

  memo2.Lines.Add('-------------------------------------------------');
  for i:=1 to yuanNum do
     memo2.Lines.Add(inttostr(i)+' ('+floattostr(yuan[i].x)+','+floattostr(yuan[i].y)+') r='+floattostr(yuan[i].r));
  
end;

procedure TForm1.BitBtn1Click(Sender: TObject);
begin
  Memo1.Lines.Add(Labelededit1.Text+','+Labelededit2.Text);
  inc(Num);
  pt[Num].x:=strtofloat(Labelededit1.Text);
  pt[Num].y:=strtofloat(Labelededit2.Text);
end;

procedure TForm1.BitBtn2Click(Sender: TObject);
begin
  Num:=0;
  memo1.Lines.Clear;
  Memo2.Lines.Clear;
end;

end.